New immunoregulatory protein lst-1

ABSTRACT

The invention concerns a new immunoregulatory protein LST-1, nucleic acid sequences coding for this protein, a process for the isolation of this protein, as well as its use for the production of a therapeutic agent. The DNA and protein sequences are shown in SEQ ID NO; 1 to 4.

[0001] This invention relates to a new leukocyte specific andimmunoregulatory protein (LST-1) and to the corresponding proteinproduced by recombinant techniques as well as nucleic acids which codefor proteins with LST-1 activity, methods of use and of production.

[0002] Cytokines are proteins with a molecular weight of less than 50kD, which mediate the exchange of autocrine, paracrine or endocrinesignals between the cellular components of tissues or between differenttissues. The cytokines identified so far include growth factors,interleukins and interferons and act on cells in many systems of thebody: the hematopoietic system, the immune system, the nervous system,the skeletal system, connective tissues, and probably most other tissuesand organs of the body (for reference see A. Thompson ed. (1991), TheCytokine Handbook, London, Academic Press and A. Miyajima et al., AnnualReviews Immunol. 10 (1992) 295-331). Examples of cytokines are EGF, NGF,PDGF, FGF, IL-1 to IL-7, GM-CSF, G-CSF, MCSF, IFN, TNF-α TGF-α and -β.

[0003] More than 100 cytokines have been identified so far, but there isa need for further new cytokines which might be important for potentialhealth care advances.

SUMMARY OF THE INVENTION

[0004] Accordingly it is an object of the present invention to provide anew cytokine showing new biological properties.

[0005] It is a further object of the present invention to provide thenew protein using recombinant DNA molecules capable of expressing saidprotein in order that the binding protein will be more readilyavailable. These and other objects of the invention have beenaccomplished by providing a purified protein according to the invention,selected from a group consisting of a protein which is at least 85%homologous to the amino acid sequence SEQ ID NO:3 and fragments thereof,wherein said protein is capable of binding to an antibody specific forsaid protein or its cell surface receptor on leukocytes.

DESCRIPTION OF SPECIFIC EMBODIMENTS

[0006] The invention comprises especially novel therapeutic compositionscomprising recombinant proteins produced using nucleic acid sequencesencoding proteins with LST-1 activity. The LST-1 cDNA which can be usedfor the production of the recombinant protein was initially isolatedfrom U-937 cells (DSM ACC 5) stimulated with IFN-γ RT-PCR cloning ofmRNA from these cells resulted in a cDNA clone designated pLST-1 havinga length of 636 bp. Analysis of the LST-1 cDNA reveals that LST-1consists of six exons. These exons are designated exons 1A (bp 48-162),1B (bp 544-652), 2 (bp 1044-1162), 3 (bp 1475-1567), 4 (bp 1775-1797)and 5 (bp-2325-2709). In exon 5, after position 2345, there is aninternal 5′ donor splice site. By alternative splicing, thus, twoisoforms of the LST-1 protein can be formed, which accordingly have alength of either 104 or 97 amino acids (cf. SEQ ID NOS: 3 and 4). Thehuman pLST-1 cDNA clone contains an extended 5′ region encoding stopcodons.

[0007] The invention is based on a new cytokine-like protein (denotedLST-1 protein, or LST-1, in the following) whose production isstimulated in U-937 cells by IFN-γ by a factor of more than 100preferably 1000, which binds to the surface of leukocytes and which

[0008] a) is coded by the DNA sequence shown in SEQ ID NO:2 for themature protein or by the genomic sequence shown in SEQ ID NO:1,

[0009] b) is coded by DNA sequences which hybridize under stringentconditions with the DNA sequences shown in SEQ ID NO:1 or 2 or fragmentsof the DNA sequences in the DNA region which codes for the matureprotein, or

[0010] c) is coded by DNA sequences which, if there was no degeneracy ofthe genetic code, would hybridize with the sequences defined in a) or b)and code for a polypeptide with amino acid sequence,

[0011] d) and the reading frame of said protein is defined by ATGstarting at position 1144 of SEQ ID NO:1 following within no shift ofthe reading frame in the protein coding region following said ATG.

[0012] The protein can be defined by its DNA sequence (preferably by itscDNA sequence deduced from SEQ ID NO:1) and by the amino acid sequencederived therefrom. The LST-1 protein can occur in natural allelicvariations which differ from individual to individual. Such variationsof the amino acids are usually amino acid substitutions. However, theymay also be deletions, insertions or additions of amino acids to thetotal sequence. The LST-1 protein according to the invention—depending,both in respect of the extent and type, on the cell and cell type inwhich it is expressed—can be in glycosylated or non-glycosylated formThe LST-1 proteins according to SEQ ID NO:3 and SEQ ID NO:4 arepreferred.

[0013] LST-1 mRNA is expressed constitutively in T cells, macrophages,U-937 and at low levels in human tonsilla, lung and liver, which may bedue to the lymphocytes and macrophages present in these tissues theprotein shows an immunoregulatory activity. Transcription can bestrongly enhanced by IFN-γ in U-937 cells. Upon stimulation of theJurkat T cell line (ATCC TIB 152) with TPA(12-o-tetradecanoylphorbol-13-acetate) only a short induction of LST-1mRNA was observed. An increase of mRNA expression starts after fourhours with a peak after 8 hours of stimulation and further decreaseafter 24 hours of stimulation.

[0014] “Immunoregulatory activity” means that the protein modulatesdirectly or non-directly the cooporation of T-cells with macrophages.

[0015] The binding to the surface of leucocytes is preferably estimatedin vitro. Such methods are known in the state of the art.

[0016] The term “hybridize under stringent conditions” means that twonucleic acid fragments are capable of hybridization to one another understandard hybridization conditions described in Sambrook et al.,“Expression of cloned genes in E. coli” in Molecular Cloning: Alaboratory manual (1989) Cold Spring Harbor Laboratory Press, New York,USA, 9.47-9.62 and 11.45-11.61.

[0017] More specifically, stringent conditions as used herein refer tohybridization in 1 mol/l NaCl, 1% SDS and 10% dextransulfate. This isfollowed by two washes of the filter at room temperature of 5 minutes in2×SSC and one final wash for 30 minutes. This final wash may be at0,5×SSC, 0,1% SDS, more preferably at 0,2×SSC, 0,1% SDS and mostpreferably at 0,1×SSC, 0,1% SDS, final wash taking place at 65° C. Thoseof ordinary skilled in the art will recognize to that other conditionswill afford the same degrees of stringency and are encompassed by thephraseology “under stringent conditions” and are encompassed herein.

[0018] LST-1 is a protein which is active in its glycosylated orunglycosylated form. The unglycosylated form can be produced byrecombinant technology in prokaryotic cells.

[0019] “Proteins with LST-1 activity” means also proteins with minoramino acid variations but with substantially the same LST1 activity.Substantially the same means that the activities are of the samebiological properties and preferably at least 85% homology in amino acidsequence. More preferably, the amino acid sequences are at least 90%identical. LST-1 can be purified from U-937 cells by affinitychromatography using a monoclonal antibody against LST-1. It is alsopreferred to use other known protein purification techniques, includingimmunoprecipitation, gel filtration, ion exchange, chromatography,chromatofocussing, isoelectric focussing, selective precipitation,electrophoresis, and the like. Fraction isolated during purificationprocedures can be analyzed for the presence of LST-1 activity by usingLST-1 specific antibodies.

[0020] The protein according to the invention can also be produced byrecombinant means. Non-glycosylated LST-1 protein is obtained when it isproduced recombinantly in prokaryotes. With the aid of the nucleic acidsequences provided by the invention it is possible to search for theLST-1 gene or its variants in genomes of any desired cells (e.g. apartfrom human cells, also in cells of other mammals), to identify these andto isolate the desired gene coding for the LST-1 protein. Such processesand suitable hybridization conditions are known to a person skilled inthe art and are described, for example, by Sambrook, J., et al.,“Expression of cloned genes in E. coli” in Molecular Cloning: Alaboratory manual (1989) Cold Spring Harbor Laboratory Press, New York,USA, and B. D. Hames, S. G. Higgins, Nucleic acid hybridisation—apractical approach (1985) IRL Press, Oxford, England. In this case thestandard protocols described in these publications are usually used forthe experiments.

[0021] The use of recombinant DNA technology enables the production ofnumerous LST-1 protein derivatives. Such derivatives can, for example,be modified in individual or several amino acids by substitution,deletion or addition. The derivatization can, for example, be carriedout by means of site directed mutagenesis. Such variations can be easilycarried out by a person skilled in the art (J. Sambrook, B. D. Hames,loc. cit.). It merely has to be ensured that the characteristicproperties of the LST-1 protein (inhibition of the aforementioned celllines) are preserved. The invention therefore in addition concerns aLST-1 protein which is a product of a prokaryotic or eukaryoticexpression of an exogenous DNA

[0022] The invention concerns a nucleic acid molecule for use insecuring expression in a prokaryotic or eukaryotic host cell of a LST-1protein and is selected from the group comprising

[0023] a) DNA sequences shown in SEQ ID NO:1 and 2 or the complementarysequences,

[0024] b) nucleic acid sequences which hybridize under stringentconditions with one of the sequences from a),

[0025] c) nucleic acid sequences which, if there was no degeneracy ofthe genetic code, would hybridize with one of the sequences stated in a)or b),

[0026] d) and the reading frame of said protein is defined by ATGstarting at position 1144 of SEQ ID NO:1 following within no shift ofthe reading frame in the protein coding region following said ATG.

[0027] With the aid of such nucleic acids coding for a LST-1 protein,the protein according to the invention can be obtained in a reproduciblemanner and in large amounts. For expression in prokaryotic or eukaryoticorganisms, such as prokaryotic host cells or eukaryotic host cells, thenucleic acid is integrated into suitable expression vectors, accordingto methods familiar to a person skilled in the art. Such an expressionvector preferably contains a regulatable/inducible promoter. Theserecombinant vectors are then introduced for the expression into suitablehost cells such as, e.g., E. coli as a prokaryotic host cell orSaccharomyces cerevisiae, Terato carcinoma cell line PA-1 sc 9117(Bufttner et al., Mol. Cell. Biol. 11 (1991) 3573-3583), insect cells,CHO or COS cells as eukaryotic host cells and the transformed ortransduced host cells are cultured under conditions which allow anexpression of the heterologous gene. The isolation of the protein can becarried out according to known methods from the host cell or from theculture supernatant of the host cell. Such methods are described forexample by Ausubel I., Frederick M., Current Protocols in Mol. Biol.(1992), John Wiley and Sons, New York. Also in vitro reactivation of theprotein may be necessary.

[0028] In addition the invention concerns a process for obtaining aLST-1 protein by isolation of the culture supernatant of the U-937 cellline by means of a gel chromatographic separation and purification of afraction.

[0029] The detection of transformed or transduced host cells whichrecombinantly produce the LST-1 protein and the purification of theprotein are preferably carried out by means of antibodies which bind tothis protein. Such antibodies can be obtained in a simple manneraccording to known methods by using the protein according to theinvention as an antigen or an immunogen.

[0030] The invention therefore in addition concerns the use of theprotein with LST-1 activity according to the invention for theproduction of antibodies which bind to this protein.

[0031] Anti-LST-1 antibodies are produced by immunization andappropriate vertebrate host with purified LST-1 or polypeptidederivatives of LST-1, preferably with an adjuvant. Said techniques arewell-known in the literature and are described, for example, by Harlowand Lane eds., Antibodies: A laboratory manual (1988), Cold SpringHarbor Laboratories Press.

[0032] For this, animals which are usually used for this purpose, suchas in particular, sheep, rabbits or mice, are immunized with the proteinaccording to the invention and subsequently the antiserum is isolatedfrom the immunized animals according to known methods or spleen cells ofthe immunized animals are fused with immortalized cells, such as e.g.myeloma cells, according to the method of Köhler and Milstein (Nature256 (1975) 495-497). Those cells which produce a monoclonal antibodyagainst the LST-1 protein are selected from the hybridoma cells obtainedin this way and cloned. The monoclonal or polyclonal antibodies obtainedin this way can be bound to a support material, such as e.g. cellulose,for an immunoabsorptive purification of the melanoma-inhibiting protein.Furthermore, antibodies of this kind can be used for the detection ofthe LST-1 protein in samples, such as e.g. cut tissue or body fluids.

[0033] The invention therefore additionally concerns antibodies againstthe LST-1 protein which are obtainable by immunizing an animal with aLST-1 protein and isolating the antibodies from the serum or spleencells of the immunized animals.

[0034] It has in addition turned out that the LST-1 protein has animmunoregulatory activity.

[0035] The invention in addition concerns the use of a protein accordingto the invention for the production of a therapeutic agent which can beused in tumor therapy or as an immunoregulating agent.

[0036] The protein according to the invention is processed, if desiredtogether with the usually used auxiliary agents, fillers and/oradditives, in a pharmaceutical formulation for the said therapeuticapplications.

[0037] The invention therefore in addition concerns a therapeuticcomposition containing a LST-1 protein according to the invention and ifdesired together with the auxiliary agents, fillers and/or additivesthat are usually used.

[0038] The invention further concerns the use of sequences of the LST-1gene, preferably nucleic acid molecules coding for a protein havingLST-1 activity, or activating polynucleotides from the 5′ untranslatedregion, in gene therapy, and in particular, for the production ofmedicaments for gene therapy.

[0039] Gene therapy of somatic cells can be accomplished by using, e.g.,retroviral vectors, other viral vectors, or by non-viral gene transfer(for clarity cf. T. Friedmann, Science 244 (1989) 1275; Morgan 1993, RACDATA MANAGEMENT REPORT, June 1993).

[0040] Vector systems suitable for gene therapy are, for instance,retroviruses (Mulligan, R. C. (1991) in Nobel Symposium 8: Ethiology ofhuman disease at the DNA level (Lindsten, J. and Pattersun Editors)143-189, Raven Press), adeno associated virus (McLuglin, J. Virol. 62(1988), 1963), vaccinia virus (Moss et al., Ann. Rev. Immunol. 5 (1987)305), bovine papilloma virus (Rasmussen et al., Methods Enzymol. 139(1987) 642) or viruses from the group of the herpes viruses such asEpstein Barr virus (Margolskee et al., Mol. Cell. Biol. 8 (1988) 2937)or herpes simplex virus.

[0041] There are also known non-viral delivery systems. For this,usually “nude” nucleic acid, preferably DNA, is used, or nucleic acidtogether with an auxilary such as, e.g., transfer reagents (liposomes,dendromers, polylysine-transferrine-conjugates (Felgner et al., Proc.Natl. Acad. Sci. USA 84 (1987) 7413).

[0042] Another preferred method of gene therapy is based on homologousrecombination. In this, either the gene coding for the LST-1 protein canbe inserted in one or more copies into the genome of somatic cellsand/or the LST-1 gene endogenously present in the cells can bemodulated, preferably activated.

[0043] Methods of homologous recombination are described, e.g., inKucherlapati, Proc. in Nucl. Acids Res. and Mol. Biol. 36 (1989) 301;Thomas et al., Cell 44 (1986) 419428; Thomas and Capecchi, Cell 51(1987) 503-512; Doetschman et al., Proc. Natl. Acad. Sci. USA 85 (1988)8583-8587 and Doetschman et al., Nature 330 (1987) 576-578. In thesemethods, a portion of DNA to be integrated at a specific site in thegenome (gene fragment of LST-1) is bound to a targeting DNA. Thetargeting DNA is a DNA which is complementary (homologous) to a region(preferably within or proximal to the LST-1 gene) of the genomic DNA.When two homologous portions of a single-stranded DNA (e.g. thetargeting DNA and the genomic DNA) are in close proximity to one anotherthey will hybridize and form a double-stranded helix. Then the LST-1gene fragment and the targeting DNA can be integrated into the genome bymeans of occurrence of recombination. This homologous recombination canbe carried out both in vitro and in vivo (in the patient).

[0044] Preferably, there is used a DNA which codes for a protein havingLST-1 activity, a fragment which inhibits LST-1 expression (knock-outsequence) or a fragment capable of activating, after integration of thegenome of a cell, expression, in this cell, of a protein having LST-1activity. Such a fragment may be, for example, a promoter and/orenhancer region which is heterologous to the corresponding LST-1 regionor which, after integration into the LST-1 gene, activates the actuallysilent or to a little extent expressed LST-1 gene transcriptionallyand/or translationally.

[0045] Thus, by means of this DNA, one or more LST-1 genes are newlyintroduced into the target cell, or the essentially transcriptionallysilent gene in the genome of a mammalian cell is activated in suchfashion that the mammalian cell is enabled to produce endogenous LST-1protein. To this end, a DNA construct is inserted into the genome byhomologous recombination, the DNA construct comprising the following: aDNA regulatory element capable of stimulating expression of this gene ifoperatively linked thereto; and one or more DNA target segments whichare homologous to a region in this genome, which region is within orproximal to this gene. This construct is inserted into the genome of themammalian cell in such fashion that the regulatory segment isoperatively linked to the gene which codes for the protein having LST-1activity. Preferably, the construct further comprises amplifyingsequences, especially if genes coding for proteins with LST-1 activityare inserted into the cell.

[0046] For the introduction of LST-1 genes into the target cells, theconstruct comprises a regulatory element, one or more LST-1 genes andone or more target segments. The target segments are chosen in such away that they hybridize with an appropriate region of the genome,whereby, after homologous recombination, the inserted exogenous LST-1genes are expressed.

[0047] There are known a large number of processes by which homologousrecombination can be initiated. Preferably, homologous recombinationtakes place during DNA replication or mitosis of the cells. A DNA ofthis kind can be used for the production of an agent for therapeutictreatment of tumors or for the production of homologous or heterologousLST-1 protein in a host organism.

[0048] It is possible to provide a test on the basis of the nucleic acidsequences of the LST-1 protein provided by the invention which can beused to detect nucleic acids which code for LST-1 proteins. Such a testcan for example be carried out in cells or cell lysates and by means ofnucleic acid diagnostics. In this case the sample to be examined isbrought into contact with a probe which would hybridize with the nucleicacid sequence coding for the LST-1 protein. A hybridization between theprobe and nucleic acids from the sample indicates the presence ofexpressed LST-1 proteins. Such methods are known to a person skilled inthe art and are for example described in WO 89/06698, EP-A 0 200 362,USP 2915082, EP-A 0 063 879, EP-A 0 173 251, EP-A 0 128 018. In apreferred embodiment of the invention, the nucleic acid of the samplewhich codes for a LST-1 protein is amplified before testing, e.g. by thewell-known PCR technique. A derivatized (labelled) nucleic acid probe isusually used in the field of nucleic acid diagnostics. This probe isbrought into contact with a carrier-bound denatured DNA or RNA from thesample and in this process the temperature, ionic strength, pH value andother buffer conditions are selected in such a way that—depending on thelength of the nucleic acid sample and the resulting melting temperatureof the expected hybrid—the labelled DNA or RNA can bind to homologousDNA or RNA (hybridization, see also Southern, E. M., J. Mol. Biol. 98(1975), 503-517; Wahl, G. M. et al., Proc. Natl. Acad. Sci. USA 76(1979), 3683-3687). Suitable carriers are membranes or carrier materialsbased on nitrocellulose (e.g. Schleicher and Schüll, BA 85, AmershamHybond, C.), reinforced or bound nitrocellulose in a powder form ornylon membranes derivatized with various functional groups (e.g. nitrogroup) (e.g. Schleicher and Schüll, Nytran; NEN, Gene Screen; AmershamHybond M.; Pall Biodyne).

[0049] The hybridized DNA or RNA is then detected by incubating thecarrier, after thorough washing and saturation to prevent unspecificbinding, with an antibody or antibody fragment. The antibody or antibodyfragment is directed towards the substance incorporated into the nucleicacid probe during the derivatization. The antibody is in turn labelled.It is, however, also possible to use a directly labelled DNA Afterincubation with the antibodies, it is washed again in order to onlydetect specifically bound antibody conjugates. The determination is thencarried out via the label of the antibody or antibody fragment accordingto well-known methods.

[0050] The detection of the LST-I expression can be carried out forexample as:

[0051] in situ hybridization with immobilized whole cells usingimmobilized tissue smears and isolated metaphase chromosomes,

[0052] colony hybridization (cells) and plaque hybridization (phages andviruses),

[0053] Northern hybridization (RNA detection),

[0054] serum analysis (e.g. cell type analysis of cells in serum byslot-blot analysis),

[0055] after amplification (e.g. PCR technique).

[0056] The invention therefore includes a method for the detection ofnucleic acids which code for a LST-1 protein which is characterized inthat the sample to be examined is incubated with a nucleic acid probewhich is selected from the group comprising

[0057] a) the DNA sequences shown in SEQ ID NOS:1 and 2 or acomplementary sequence to these,

[0058] b) nucleic acids which hybridize under stringent conditions withone of the sequences from a),

[0059] the nucleic acid probe is incubated with the nucleic acid fromthe sample and the hybridization of the nucleic acid in the sample andnucleic acid probe is detected, if desired, via a further bindingpartner.

[0060] Thus, LST-1 is a valuable prognostic marker in tumor diagnostics(metastasis, progress) and an activity marker for cell proliferation,especially for T cell leukemic cells.

[0061] The human histiocytic lymphoma cell line U-937 was accorded thedeposit number DSM ACC 5 and has since 3 April 1990 been contained in,and freely accessible at, the public collection of Deutsche Sammlung vonMikroorganismen und Zellkulturen GmbK Mascheroder Weg 1b, D-38124Braunschweig.

[0062] Plasmid pLST-1 which contains the LST-1 gene was deposited byBoehringer Mannhein GmbH at the Deutsche Sammlung von Mikroorganismenund Zellkulturen GmbH, Mascheroder Weg 1b, D-38124 Braunschweig on May24, 1995 and assigned the number DSM 10011.

[0063] The invention is elucidated in more detail by the sequencelisting in conjunction with the following examples. In this case SEQ IDNO 1 denotes the nucleotide sequence of the LST-1 genomic region. Apolymorphic Pvu II restriction site is at position 2841. The TATA box,the IFN-γ-activated site (FcγR1), and the interferon-stimulated genefactor-2 responsive element (ISGF-2) are starting at positions 279,1509, and 1814, respectively. The DNA sequence has been submitted toGenBank databank (accession number U00921). SEQ ID NO 2 denotes proteinand cDNA of LST-1. SEQ ID NO 3 denotes LST-1 protein sequence (104 aminoacids). SEQ ID NO 4 denotes LST-1 protein sequence (isoform 97 aminoacids)

EXAMPLE 1

[0064] Isolation of the LST-1 Genomic Region

[0065] The human B cell line CAH was established from a homozygousindividual typed HLA-A3,-Bw47, -Cw6, and -DR7. Genomic DNA was used togenerate the cosmid library cah in the vector pTCF as describedpreviously (E. H. Weiss et al., Immunobiology 170 (1985) 367-380).Several cosmids were isolated by hybridization to a TNFA probe. Asubclone derived from the cosmid cah5 containing the region upstream ofthe LTB gene was obtained by Hind m endonuclease restriction of cah5.Religation of the digest resulted in a truncated clone (cah5dH3) of 18kb length. Five adjacent Pst I fragments of 1.5 kb, 0.8 kb, 3.1 kb, 0.4kb and 0.7 kb referred to as Pst6, Pst4, and Pst11, Pst400 and Pst700respectively, were isolated and subcloned into the vector pUC19.

EXAMPLE 2

[0066] Determination of the Nucleotide Sequence

[0067] The subclones Pst4, Pst6, and Pst11 and two additional 5′ PstIfragments of 400 and 700 bp respectively (Pst400 and Pst700) weresequenced in both directions with the dideoxynucleotide chaintermination method using either Sequenase 2.0 (USB, Braunschweig,Germany) or T7 polymerase (Pharmacia, Freiburg, Germany). The genomicorganization of these fragments was determined by direct sequencing ofcah5dH3 across the Pst I restriction sites, employing oligonucleotides.This confirmed the order and excluded the possibility that any smallfragment is situated between the restriction fragments Pst6, Pst4,Pst11, Pst400 and Pst700.

EXAMPLE 3

[0068] Cell Culture and Stimulation Experiments

[0069] Non-adherent human Jurkat T cells, the human histiocytic cellline U-937, and the human monocytic cell line MonoMac6 were grown inRPMI 1640 medium. The adherent A431 and HeLa epithelial carcinoma lineswere grown in Dulbecco's modified Eagle's medium (DMEM). For both media10% heat inactivated fetal calf serum, 1% penicillin/streptomycin and 1%L-glutamine (all purchased from Gibco-BRL, Berlin, Germany) were used asa supplement. All cells were cultured at 5% CO₂ and 37° C. in ahumidified atmosphere. Stimulation of Jurkat cells was carried out with50 ng/ml 12-O-tetradecanoylphorbol-13-acetate (TPA) (Sigma, Deisenhofen,Germany) and 5 μg/ml phytohemagglutinin (PHA) (Sigma). The humanmonocytic cell line MonoMac6 was stimulated with 1 mg/mllipopolysaccharides (prepared from Salmonella minnesota; Sigma) for 4hours. The histiocytic cell line U-937 was stimulated with 200 U/mlinterferon-γ for 48 hours.

EXAMPLE 4

[0070] Cloning, Characterization and Expression of the LST-1 cDNA

[0071] Reverse transcription of RNA, followed by the polymerase chainreaction (RT-PCR) of mRNA isolated from U-937 cells stimulated withinterferon-γ, resulted in a cDNA clone, designated pLst1 of 636 bplength. This is in good agreement with the size of mRNA detected byNorthern blot of about 800 ,bp length, due to an expected length of thepoly(A) tail of about 200 bp. The cDNA sequence of pLst1 was identicalto the coding regions of the genomic sequence cloned from a differenthuman cell line. Sequence analysis revealed three regions which are wellconserved between the human LST-1 and the mouse B 144 transcript, andcould be assigned to exon 24 of the human gene.

[0072] Like the other genes in the TNF region, LST-1 consists of sixexons (1A, 1B, 2, 3, 4, 5) and five introns. Its transcriptionorientation is the same as for TNFA an TNFB, but opposite to theneighboured LTB gene. This result does not agree with the orientation ofthe mouse B144 gene as marked in the organization of the H-2D^(b) regionpublished by J. N Wroblewski et al., Immunogenetics 32 (1990) 200-204.The human pLst1 cDNA clone contains an extended 5′ region encoding stopcodons in all three reading frames and can therefore be considered to befull length. The LST-1 cDNA potentially encodes a transmembrane protein.

[0073] The LST-1 cDNA can be expressed in prokaryotes, preferably inE.coli, using an appropriate vector (e.g. pBR 322). The protein can beisolated either after secretion or from cytoplasmatic accumulatedinclusion bodies and subsequent naturation.

EXAMPLE 5

[0074] Expression of LST-1

[0075] LST-1 mRNA is expressed constitutively in T cells, macrophages,U-937, and at low levels in human tonsilla, lung, and liver, which maybe due to lymphocytes and macrophages present in these tissues. Inepithelial cell lines such as HeLa and A431 cells, no LST-1 transcriptswere detectable (data not shown). This expression pattern prompted us toname the corresponding gene Leucocyte Specific Transcript-1 (LST-1).Transcription levels can be strongly enhanced in U-937 cells bystimulation with interferon-γ, but not by lipopolysaccharides in themacrophage cell line MonoMac6. Stimulation of the Jurkat T cell linewith TPA (12-O-tetradecanoylphorbol-13-acetate) induced transientexpression of LST-1 mRNA above the constitutive level. Followinginduction, the mRNA expression level increased after 4 hours with a peakat 8 hours and decreased after 24 hours of stimulation.

LIST OF REFERENCES

[0076] Ausubel, I., Frederick, M., Current Protocols in Mol. Biol.(1992), John Wiley and Sons, New York

[0077] Büttner et al., Mol. Cell. Biol. 11 (1991) 3573-3583

[0078] Doetschman et al., Nature 330 (1987) 576-578

[0079] Doetschman et al., Proc. Natl. Acad. Sci. USA 85 (1988) 8583-8587

[0080] EP-A0 173 251

[0081] EP-A 0 063 879

[0082] EP-A 0 128 018

[0083] EP-A 0 200 362

[0084] Felgner et al., Proc. Natl. Acad. Sci. USA 84 (1987) 7413

[0085] Friedmann, T., Science 244 (1989) 1275; Morgan 1993, RAC DATAMANAGEMENT REPORT, June 1993

[0086] Hames, B. D., Higgins, S. G., Nucleic acid hybridisation—apractical approach (1985) IRL Press, Oxford, England

[0087] Harlow and Lane eds., Antibodies: A laboratory manual (1988),Cold Spring Harbor Laboratories Press

[0088] Köhler and Milstein, Nature 256 (1975) 495497

[0089] Kucherlapati, Proc. in Nucl. Acids Res. and Mol. Biol. 36 (1989)301

[0090] Margolskee et al., Mol. Cell. Biol. 8 (1988) 2937

[0091] McLughlin, J. Virol. 62 (1988), 1963

[0092] Miyajima, A., et al., Annual Reviews Immunol. 10 (1992) 295-331

[0093] Moss et al., Ann. Rev. Immunol. 5 (1987) 305

[0094] Mulligan, R. C. (1991) in Nobel Symposium 8: Etiology of humandisease at the DNA level (Lindsten, J. and Pattersun Editors) 143-189,Raven Press

[0095] Rasmussen et al., Methods Enzymol. 139 (1987) 642

[0096] Sambrook, J., et al., “Expression of cloned genes in E. coli” inMolecular Cloning: A laboratory manual (1989) Cold Spring HarborLaboratory Press, New York, USA, 9.47-9.62 and 11.45-11.61

[0097] Southern, E. M., J. Mol. Biol. 98 (1975), 503

[0098] Thomas and Capeechi, Cell 51 (1987) 503-512

[0099] Thomas et al., Cell 44 (1986) 419428

[0100] Thompson, A, ed. (1991), The Cytokine Handbook, London, AcademicPress U.S. Pat. No. 2,915,082

[0101] Wahl, G. M. et al., Proc. Natl. Acad. Sci. USA 76 (1979),3683-3687

[0102] Weiss, E. H., et al., Immunobiology 170 (1985) 367-380 WO89/06698

[0103] Wroblewski, J. M., et al., Immunogenetics 32 (1990) 200-204

1 4 5581 base pairs nucleic acid double linear DNA (genomic) notprovided exon 48..162 exon 544..652 exon 1044..1162 exon 1475..1567 exon1775..1797 exon 2325..2709 1 GAGCCGAACT TCCTCTCCTA ACAATGCTGG GGAGGAACCCAGCCTGGGGG AGAAGTTAAA 60 GCCAGAGGAG GGGCAGGAAT GTCTGAGGTG GCAACACTTCTCTTCAGCCA GACAGCACTG 120 GCCAGTTTGG AGTCTGTCCA TCCTGCAGGC CACAAGCTCTGGGTAAGCTG GGAATGGGCA 180 GGGACCTTGG TGGAAGGATG GTCACACCCC AGAGTGGGGTGAAGCTAAGA TGAGGGGAGG 240 GAGAGTATGG GTTTGAGTTT CCCTGGGCCG TCGAGGAATCCTCTGAGTCT CTGCTCCCCA 300 AAGAAATTAA AGACAATTCA TTTCTGTGCC CACGGCCCTTATGGCTCCAC CTGCACTTCT 360 GCTCCCCACC CCCCAGAATT CCTCTTAAAC CCAGAAGGTCCCAGTTTCCA GACCCTAGTC 420 AGTATATCTG GCTCTGGGGT GAAGAGAACG GCCCCCTCTTCACCCTCAAA CAGGAACCAG 480 TGGTTGGAGG GGAGGAAGTG CCTGAGGGGA AGTTATGGGGCCCCAGATAC TCCTCCATGC 540 CCCACTTCAG CCCTAGCAGC ATCTGCCTGT GGGAAGCAGCTCTCCACACC AGCCAAGGGG 600 GCCCCCACAC TCCCGCGCTG CTCTGCGGCT CAGGGAGCAGCCCACCTGCT GGGTGTGCTG 660 ATATCACCCT CCCTTCTTCC CCCCAGTGCC CACACCCACCCAGGCCCAGG CTCCTTCCCC 720 TCCATCATCC CCTTACCAGC ACCTAGAACC ATCCAGGGCTGAAAAGTCCC CTCCAAACCA 780 CGTGGTCAGC CCAGGGCAGA GGAAAGGGCT GGGCTCTGGAGTTGGGCAGA GCTGGCCTTA 840 AACCCCAGCT CCACCTTTCT GGGATGGGTG ACCTAGTAAAGTCCAGGCTT GAATCTCGGG 900 TCTTTACTTG GGCAACGGGC ACCATGATAC CCTATGTTCTGGGGATTAGC AGTGAGGAAT 960 GGAAAGTGCC CAGCTCGGGT TGGCACATAA GGGAGGCTCCCCAGCCTGGG AACGATTATA 1020 ACAGAGGGCC CCTCACTTCA CAGATGAGGA ACTTGAGGCAAGTCACCAGC CCCTGATCAT 1080 TTCGCCTAAA AGAGCAAGGA CTAGAGTTCC TGACCTCCAGGCCAGTCCCT GATCCCTGAC 1140 CTAATGTTAT CGCGGAATGA TGGTAAGTAA AGTGTCTCTTGCATCTGCAT AGAGAGAGTC 1200 CTGGGAGCTT AGGAAGTGAT GGGGAACAGT GATGTATGCAGCTTGGACAG GCCTCTGGGG 1260 ACAGCTGGTA CAGGAGGGAA AGGGACCTCA CGGGAGGCCCAGAAACCTGG TAAGAGGTGA 1320 GGTATTAAGG TCTGGGATGG AGAAGCTCTG AGGGTATATTTTTCTGCCTC TAAAACTGTT 1380 GGAGAGGGAA TCTGAGAAAG CTGCAACCAA CCAGGAGGCTGGGGTACGCT GGAGAAGGAA 1440 TGGGCTTCCT AACCTTGAGC CCTCTTCCCT GAAGATATATGTATCTACGG GGGCCTGGGG 1500 CTGGGCGGGC TCCTGCTTCT GGCAGTGGTC CTTCTGTCCGCCTGCCTGTG TTGGCTGCAT 1560 CGAAGAGGTG AGCGCTGCAC TCCCTCCCTC CCCCTGCAGCAGTGCCCCCT GTGCCCCCAC 1620 CCCCACACGC TTTCCCACTG CTTTCCCAGA ACACTGCCTGGCCCTGGAGC CACTGGGAAG 1680 CCAACAGGGG AGTCCACGCC TGCTGGTGGG GGGAGCCCGGGAGGCGGGAG AAGCACAAAG 1740 GGTGGGCTGT GTTGAGCTTC TTCTTTTCTT CCAGTAAAGAGGCTGGAGAG GAGCTGGGTG 1800 AGTCTGGGGA CAGGGAAGGG GGAGGGCAAG AGAGATCCTGAGTGGGTGAG TGGGGAGAAG 1860 CATGGCTGAG CGCTGAGAGG AGGGTTGGGG ACGGGAGACAAGGAGAGAGA AAGTAGGAGC 1920 ATGAGAGAGG CAGAGAAAAT CGAGGCAAAA GAGAAAGAGAAAATGAGACA GAAACCAAGA 1980 GAAAAAGTGA GACAGAGGAT AGGAGAGACA GGGAGAAAATGAGAGTGAGA GAGACACAAA 2040 GAGAAGAGCA ATGAAAGAGA GAGAGAGAGA GAGGCTCCAGAACCAGGCAC AGTGGCTCAC 2100 GTCTGTCATT CCACTATCGC AAGGCTGAGG CAGGAAGATAGCTTGAGCTC AGGGGTTGAA 2160 GACAATCCTG GACAACATAG TGGACTCTGT CTCCAAAGAAAAAAGAGAGA GAGAGAGAGA 2220 GAGAGAGAGA GGGAGAGAGA GAGAGAGAGA GGGAGAGAAGTAAGAAAGGC TGGAGGTGGG 2280 AGCAGAACTC ACAGGGAAGG ATCTGACGCA TCGCCTCCCATCAGCACCTT CTGTCCTGGT 2340 CCCAGGCCCA GGGCTCCTCA GAGCAGGAAC TCCACTATGCATCTCTGCAG AGGCTGCCAG 2400 TGCCCAGCAG TGAGGGACCT GACCTCAGGG GCAGAGACAAGAGAGGCACC AAGGAGGATC 2460 CAAGAGCTGA CTATGCCTGC ATTGCTGAGA ACAAACCCACCTGAGCACCC CAGACACCTT 2520 CCTCAACCCA GGCGGGTGGA CAGGGTCCCC CTGTGGTCCAGCCAGTAAAA ACCATGGTCC 2580 CCCCACTTCT GTGTCTCAGT CCTCTCAGTC CATCTCGAGCCTCCGTTCAA ATTGATCATC 2640 ATCAAAACTT ATGTGGCTTT TTGACCTTTG AATAGGGAATTTTTTAAATT TTTTAAAAAT 2700 TAAAATAAAA AAAACACATG GCTCACCCTT CCACCCACTCTGGGGTCAAA TAGTAATTTG 2760 TTGGGTGAAT GACAGTGTTC AGGGACCCAA GCTCCCCTAACAGCCAGAAG AGGGTATGTG 2820 TGGGCCTGGC AGGAAAGGGC AGTTGCCAAG GAGGAGTCATATCTGATCCT TCCCATTTCT 2880 CAGGACAATC AGGCTCAGCC TCCTGGGACT GGGGGAAGCAGATGTGCTGA GCTCCCACAT 2940 GGTGGTGGGA GGGGCGCTGG GACCACAGCC GGCAGCTGCCTTCTTGGACC TTTCCAGGTC 3000 AGACCTGGTG GAAGGGAAAG TTCAGAGTTG GGGGAATCCGGAGAGAGTAG ATTTGGCATC 3060 TGGAGAATGG AGAAGAAAAC ACTTGAGACT CATGAGGAGTTAGTGGTGGG GCAGATTTAT 3120 TGGGGTCTTT TGAAGAGGAC TAGGGACATC TGGGCTCTGGAATCACTCCT CGGGGCCCAT 3180 CTGAGGAGTG GCAGTGTGTT CCCATGTGAC AGTGGCCTGGTCAGAGAGAG GACAGGAGCT 3240 GCTCAGTGTT GCAGTCCCGA GGCTCTCCTC TTCCTGGTCTCTGTCCTCCC TCCTCCCACT 3300 CTCTTACTGC CCCTCCCATC CCGTCCACTA TTGCCCCTGGCTCCATTACT CACATTTGCC 3360 CTGGTAATAG ACGGTGCTGC CCACGGCCAC AGAGAGAAAGCTGACAGCAT AGAATCCAGC 3420 CCGAAGAGGA GGACTGTACC AGCCCCCTAG CTGAGGATGTTCTGCATGGG GCAATGGAGA 3480 CGGGGGTTGG GGAAGAAGTG CACACAGGCT CAGGGAGGGAAGGGGCCTCA GAGGAGCATC 3540 CCTGCCTCCC AAGGACATTG CCTCTTGGGC CTCCAGCCAGGAGGAGACAC CACCTCCCAG 3600 CATCTCACCT TTCTCCACCA CCAGCCGAGT CCCATTCCCTGTCCCGACAC CAAGGCCCAG 3660 CACCTCCACT CTGCACACGT AGATGCCTGG CGTCATGGCCTCGCACGTCC CGGATGTGCA 3720 GCTCAGCCTG GTGGTCATGG AGGAAACGGG AAGAAGCAGATGGAGGCGGC CCCTGAACTC 3780 TGGGGTTCCA TTCCTCACCT CCTTCCCTGG AACCACCTCATCTCGGAACC ACGTGACGGA 3840 GCCAATGGCC AGTCTCCCTT GGCTGGCATT GAAGGAGCAGGGCAGGAAGG CAGAGGATCC 3900 TTCCAGGGTA CGAATCTCAG GGGGCTGGGA CACCCAGAGAGCACAGGAAT CCTGGGGGGA 3960 AAAGGGAGAC CCAGAGAAAC ACCTCCCCAG TTATTCCAAAGAGAAAAGAC AACAGAGCTT 4020 GGAGTAGAAC ATCCCAGCTT TCTCCAGGCA TAGGGTGCATGGGAATAGAT ACTTTGGGGC 4080 CTCATTAAAC CCTTCCCTCT TAACCAATCT GATTTCTTAACATTGCTTAT TAAATCATTT 4140 TTCGGCTGGG TGCAGTCGCA CGCCTGTAAT CCCAGCACTTTGGGAGGCCG AGGTGGGCGG 4200 ATCACCAGGT CAGGAGATCG AGACCATCCT GGCCAACATGGTGAAACCCC GTCTCTACTA 4260 AAAAAATACA AAAATTAGCC GGGCATGGTG GTGTGCACCTGTAATCCCAG CTACTCGGGA 4320 GGCTGAGGCA GGAGAATCGC TTGAACCCGG GAGGCAGAGGTTGCAGTGAG CCAAGATTGC 4380 GCCATTGCAC TCCAGCCTGG GCGACAAAGC AAGACTCCATCTCAAAAAAT AAAAAATAAA 4440 AATCATTTTT CAAATTCTTC CTATACCAAC TCTCACTCTCACCCTCTGCC ATCATTCTCC 4500 AGCCAGTTCA GTAGTAACTT GTCTAGCTGA AATGTAAACCATCATGGTGA AATTAAGCTC 4560 ATTAATGAAT TGCAGCTGCC TAGTTAACTA ATATCACTCATTATATTATG CAGGTATTAT 4620 TTTAGTACAA ATGGCATTGT ACAGTAAGCC ATCCTTCCTCTTTTTCTTTT TTCTTTTTTT 4680 GAGATGGGGT CTTGCTCTGT TGCCCAGGCT GGAATGCAGTGGTGCAATCT TGGCTCACTG 4740 CAAACTCCGT CCCCTGGGTT CAAGCGATCC TGGTGCCTCAGCCTCCCAAG TAGCTGGGAC 4800 TACAGGCACC CACCACCACG ACTGGCTAAT TTTTGTATTTTCAGTCGAGA CAGGGTTTCC 4860 ACCATCTGGT CTCAAACTCC TGACCTCAAG TGATCCACCCACCTCGGACC AGGCTGGCTC 4920 AAACTCCTGA TCTCAAGTGA TCCACCTGCC TCGGCCTCCCAAAGTGCCAC CCAGCCACTC 4980 TTGGTTTTCG TTAAAGAAAG TAACTAATTA AATCTCCAGGTGAAGACGTG GCCTTAATTG 5040 GTTGAGATTC CTATTTAACC CGTCCATGTT GATGAATTAAACCAAATATT AAAATCCCTG 5100 ATTAAATTAT CTACTTAGGG AAATTTACAA GTCATTCTATTTCAGTGGTT CTCAAACTTG 5160 AGTGTGTATG GAAATTACCT GGAGCATCTG CTAGAACAGATTCCTGGGCC TACCCCCCGA 5220 GTTTTTGACT CAGTAGGTCT GGAGTGGGGC CTAAGAATTTGTTCTAGGTT CCCAGAAATC 5280 CACATTTTGA GAACTCCTGC ATTTAGTTAA TAATATGCCTGATAGTTAAG GTCTCTCAGT 5340 TCATTAAAAA CAGTTTCGGC CGGGTGCAGT TCGCACGCCTATAATCCCAA CACTTTGGGA 5400 GGCCAAGGCG AGTGGATCAC CTGAGGTCAG GAGTTTGAGACCAGCCTGGC CAACATGGTG 5460 AAACCTCGTC TCTACTAAAA ATACACAAGT TAGCCAGCAGTAATGGCATG CACCTGTAAT 5520 CCTAGCTACT TGGGAGGCTG AGACAGGAGA ATCATTTTTACCCAGGAGGT GGAGGCTGCA 5580 G 5581 312 base pairs nucleic acid doublelinear cDNA not provided CDS 1..312 2 ATG TTA TCG CGG AAT GAT GAT ATATGT ATC TAC GGG GGC CTG GGG CTG 48 Met Leu Ser Arg Asn Asp Asp Ile CysIle Tyr Gly Gly Leu Gly Leu 1 5 10 15 GGC GGG CTC CTG CTT CTG GCA GTGGTC CTT CTG TCC GCC TGC CTG TGT 96 Gly Gly Leu Leu Leu Leu Ala Val ValLeu Leu Ser Ala Cys Leu Cys 20 25 30 TGG CTG CAT CGA AGA GTA AAG AGG CTGGAG AGG AGC TGG CAC CTT CTG 144 Trp Leu His Arg Arg Val Lys Arg Leu GluArg Ser Trp His Leu Leu 35 40 45 TCC TGG TCC CAG GCC CAG GGC TCC TCA GAGCAG GAA CTC CAC TAT GCA 192 Ser Trp Ser Gln Ala Gln Gly Ser Ser Glu GlnGlu Leu His Tyr Ala 50 55 60 TCT CTG CAG AGG CTG CCA GTG CCC AGC AGT GAGGGA CCT GAC CTC AGG 240 Ser Leu Gln Arg Leu Pro Val Pro Ser Ser Glu GlyPro Asp Leu Arg 65 70 75 80 GGC AGA GAC AAG AGA GGC ACC AAG GAG GAT CCAAGA GCT GAC TAT GCC 288 Gly Arg Asp Lys Arg Gly Thr Lys Glu Asp Pro ArgAla Asp Tyr Ala 85 90 95 TGC ATT GCT GAG AAC AAA CCC ACC 312 Cys Ile AlaGlu Asn Lys Pro Thr 100 104 amino acids amino acid linear protein notprovided 3 Met Leu Ser Arg Asn Asp Asp Ile Cys Ile Tyr Gly Gly Leu GlyLeu 1 5 10 15 Gly Gly Leu Leu Leu Leu Ala Val Val Leu Leu Ser Ala CysLeu Cys 20 25 30 Trp Leu His Arg Arg Val Lys Arg Leu Glu Arg Ser Trp HisLeu Leu 35 40 45 Ser Trp Ser Gln Ala Gln Gly Ser Ser Glu Gln Glu Leu HisTyr Ala 50 55 60 Ser Leu Gln Arg Leu Pro Val Pro Ser Ser Glu Gly Pro AspLeu Arg 65 70 75 80 Gly Arg Asp Lys Arg Gly Thr Lys Glu Asp Pro Arg AlaAsp Tyr Ala 85 90 95 Cys Ile Ala Glu Asn Lys Pro Thr 100 97 amino acidsamino acid linear protein not provided 4 Met Leu Ser Arg Asn Asp Asp IleCys Ile Tyr Gly Gly Leu Gly Leu 1 5 10 15 Gly Gly Leu Leu Leu Leu AlaVal Val Leu Leu Ser Ala Cys Leu Cys 20 25 30 Trp Leu His Arg Arg Val LysArg Leu Glu Arg Ser Trp Ala Gln Gly 35 40 45 Ser Ser Glu Gln Glu Leu HisTyr Ala Ser Leu Gln Arg Leu Pro Val 50 55 60 Pro Ser Ser Glu Gly Pro AspLeu Arg Gly Arg Asp Lys Arg Gly Thr 65 70 75 80 Lys Glu Asp Pro Arg AlaAsp Tyr Ala Cys Ile Ala Glu Asn Lys Pro 85 90 95 Thr

1. Immunoregulatory protein which has a size of about 97-104 amino acidswhose production is stimulated in u-937 cells by IFN-γ by a factor ofmore than 100, which binds on the surface of leukocytes and which a) iscoded by the DNA sequence shown in SEQ ID NO:2 for the mature protein orby the genomic sequence shown in SEQ ID NO:1, or b) is coded by DNAsequences which hybridize with the DNA sequences shown in SEQ ID NO:1 or2 or fragments of these DNA sequences in the DNA region which codes forthe mature protein.
 2. Protein as claimed in claim 1 , which isobtainable from the cell culture supernatant of the cell line U-937after stimulation of the cell line by IFN-γ and purification by means ofgel chromatography and reverse phase HPLC.
 3. Protein as claimed inclaim 1 or 2 , wherein a) it is a product of a prokaryotic or eukaryoticexpression of an exogenous DNA, b) it is coded by the DNA sequence shownin SEQ ID NO:2 for the mature protein or for the protein with anN-terminal pre sequence, or by the genomic sequence shown in SEQ IDNO:1, c) it is coded by DNA sequences which hybridize with the DNAsequences shown in SEQ ID NO:1 or 2 or fragments of these DNA sequencesin the DNA region which codes for the mature protein, or d) is coded byDNA sequences which, if there was no degeneracy of the genetic code,would hybridize with the sequences defined in b) to c) and code for apolypetide with the same amino acid sequence, e) and binds on thesurface of leukocytes, f) and the reading frame of said protein isdefined by ATG starting at position 1144 of SEQ ID NO:1 following withinno shift of the reading frame in the protein coding region followingsaid ATG.
 4. Protein as claimed in claims 1 to 3 , with the amino acidsequence of SEQ ID NO:3 or
 4. 5. cDNA molecule for use in securingexpression in a prokaryotic or eukaryotic host cell of a protein asclaimed in one of the claims 1 to 4 , wherein the sequence of thenucleic acid molecule is selected from the group comprising a) DNAsequences shown in SEQ ID NO:1 or 2 or the complementary DNA sequences,b) nucleic acid sequences which hybridize with one of the sequences froma), c) nucleic acid sequences which, if there was no degeneracy of thegenetic code, would hybridize with one of the sequences stated in a) orb), d) and the reading frame of said protein is defined by ATG startingat position 1144 of SEQ ID NO:1 following within no shift of the readingframe in the protein coding region following said ATG.
 6. Plasmid DSM1001 l.
 7. DNA molecule having the sequence shown in SEQ ID NO:2. 8.Recombinant expression vector containing a nucleic acid which codes fora protein as claimed in claims 1 to 4 and which expresses the proteincoding nucleic acid in a transformed microorganism or a transformedeukaryotic cell.
 9. A prokaryotic or eukaryotic host cell which istransfected with a cDNA which codes for a protein as claimed in claims 1to 4 and which can produce the said protein.
 10. The host cell asclaimed in claim 9 , which is E. coli or a mammalian cell line.
 11. Theuse of a cDNA molecule which codes for a protein as claimed in claims 1to 4 , for transfection of a prokaryotic or eukaryotic organism. 12.Process for obtaining a protein which binds on the surface of leukocytesby isolation from the culture supernatant of the cell line U-937stimulated with IFN-γ, gel chromatographic separation and purifying afraction of the supernatant that corresponds to a protein of about97-104 amino acids.
 13. Process for the recombinant production of aprotein which binds on the surface of leukocytes by expression of a cDNAas claimed in one of claims 5 or 7 in a suitable host cell and isolationof the protein from the host cell or the culture supernatant of the hostcell.
 14. Use of a protein which binds on the surface of leukocytes asclaimed in one of claims 1 to 4 as an antigen or immunogen for theproduction of antibodies which bind to this protein.
 15. Antibodyagainst a protein according to claims 1 to 4 , which is obtainable byimmunizing an animal with a protein as claimed in one of claims 1 to 4and isolating the antibodies from the serum or spleen cells of theimmunized animals.
 16. Use of a protein as claimed in claims 1 to 4 ,for the production of a therapeutic agent, which can be used as animmunoregulatory agent.
 17. Therapeutic composition containing a proteinas claimed in one of claims 1 to 4 , if desired together withpharmaceutical auxiliary substances, fillers and/or additives. 18.Method for the detection of nucleic acids that code for a proteinaccording to claims 1 to 4 , wherein the sample to be examined isincubated with a nucleic acid probe which is selected from the groupcomprising a) DNA with sequences shown in SEQ ID NO:1 or 2 or theircomplementary sequences, b) nucleic acids which hybridize understringent conditions with one of the sequences from a), the nucleic acidprobe is incubated with the nucleic acid of the sample and thehybridization of the nucleic acid of the sample and the nucleic acidprobe is detected, if desired via a further binding partner.
 19. Methodas claimed in claim 18 , wherein the nucleic acid to be detected isamplified before detection.
 20. Process for the production of a proteinaccording to claims 1 to 4 , comprising the steps of expressing in amammalian cell the endogenous gene for this protein by inserting a DNAconstruct into the genome of the cell by homologous recombination, saidDNA construct comprising a DNA regulatory element capable of stimulatingthe expression of said gene if operatively linked thereto, and furthercomprising one or more DNA target segments homologous to a region inthis genome, which region is within or proximal to said gene; culturingthe cells and recovering said protein from the cells or the cell culturesupernatant.
 21. A process for the production of a protein as claimed inclaims 1 to 4 , comprising the steps of expressing in a mammalian cellat least one exogenous gene which codes for this protein by inserting aDNA construct into the genome of the cell by homologous recombination,said DNA construct comprising a DNA regulatory element capable ofstimulating the expression of said gene if operatively linked thereto, aDNA element which codes for said protein and further comprising one ormore DNA target segments homologous to a region in this genome,culturing the cells and recovering the LST-1 protein from the cells orcell culture supernatant.
 22. The use of a DNA construct which can beintroduced into the genome of mammalian cells by homologousrecombination, said DNA construct comprising a DNA regulatory elementcapable of modulating the expression of a gene if operatively linkedthereto, said gene coding for a protein accordig to claims 1 to 4 , andone or more DNA target segments homologous to a region in this genome,which region is within or proximal to said gene, and wherein saidconstruct can be inserted into said genome of the mammalian cell in suchfashion that the regulatory element is operatively linked to the genecoding for said protein, for preparing a tumor therapeutic agent or animmunoregulatory agent.
 23. The use of a DNA construct which can beintroduced into the genome of mammalian cells by homologousrecombination, said DNA construct comprising a DNA regulatory elementcapable of modulating the expression of a gene if operatively linkedthereto,